Many components in a jet engine are designed and manufactured to withstand relatively high temperatures. Included among these components are the turbine blades, vanes, and nozzles that make up the turbine engine section of the jet engine. In many instances, various types of welding processes are used during the manufacture of the components, and to repair the components following a period of usage. Moreover, various types of welding technologies and techniques may be used to implement these various welding processes. However, one particular type of welding technology that has found increased usage in recent years is laser welding technology.
Laser welding technology uses a high power laser to manufacture parts, components, subassemblies, and assemblies, and to repair or dimensionally restore worn or damaged parts, components, subassemblies, and assemblies. In general, when a laser welding process is employed, laser light of sufficient intensity to form a melt pool is directed onto the surface of a metal work piece, while a filler material, such as powder, wire, or rod, is introduced into the melt pool. Until recently, such laser welding processes have been implemented using laser welding machines. These machines are relatively large, and are configured to run along one or more preprogrammed paths.
Although programmable laser welding machines, such as that described above, are generally reliable, these machines do suffer certain drawbacks. For example, a user may not be able to manipulate the laser light or work piece, as may be needed, during the welding process. This can be problematic for weld processes that involve the repair or manufacture of parts having extensive curvature and/or irregular or random distributed defect areas. Thus, in order to repair or manufacture parts of this type, the Assignee of the present application developed a portable, hand-held laser welding wand. Among other things, this hand-held laser welding wand allows independent and manual manipulation of the laser light, the filler material, and/or the work piece during the welding process. An exemplary embodiment of the hand-held laser welding wand is disclosed in U.S. Pat. No. 6,593,540, which is entitled “Hand Held Powder-Fed Laser Fusion Welding Torch,” and the entirety of which is hereby incorporated by reference.
The hand-held laser welding wand, such as the one described above, provides the capability to perform manual 3-D adaptive laser welding on components. However, in its present configuration the welding wand is, in many instances, used within an enclosed chamber that provides an inert atmosphere. This is because many of the materials that are welded using the hand-held wand need to be in an inert atmosphere when being welded. While such an arrangement is possible in most cases, it may present an inconvenience in certain instances. For example, it may be needed or desired to conduct a particular weld repair operation at a time or place where an enclosed inert chamber may not be available or there may not be sufficient room to provide such a chamber.
In addition to the above, because an operator holds the wand while welding a work piece, the operator's hand may be in close proximity to the work piece. When the laser light impinges on the work piece, some of the laser light may be reflected back toward the operator's hand. Moreover, some thermal radiation that is generated during the weld process may be transmitted back toward the wand and/or the operator's hand. Although the operator may likely wear gloves or other hand covering that is substantially impervious to laser light, it would be desirable to provide an additional barrier between the operator's hand and the reflected laser light.
Hence, there is a need for a device that will provide an inert atmosphere, at least at the weld pool, during welding operations with the hand-held laser welding wand, without having to provide or construct an enclosed chamber. There is additionally a need for a shield that will reflect laser light that is reflected off a work piece surface away from the hand of a hand-held laser welding wand user and/or a shield that will reflect the thermal radiation transmitted from the work piece toward the wand during the weld process. The present invention addresses one or more of these needs.